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The in August 2021 - a quick and easy guide

MOON PHASES New 8 Aug First quarter 15 Aug

Full Moon 22 Aug

Third (last) quarter 30 Aug

Events this month to look out for: 2 Moon south of M45 (morning) 3 Crescent Moon above Hyades and (morning) 5 Crescent Moon close to M35 open cluster (morning) 6 Crescent Moon forms a triangle with Castor and Pollux (morning) 8 Asteroid Vesta north of binary Porrima in Virgo (evening ) 10 Slim crescent Moon above left of (evening twilight) 12 Perseid meteor shower peak (favourable) (see below) 20 at opposition (visible all night) 20 Moon below (evening) 21 Moon below right of Jupiter (evening) 22 Full Moon below left of Jupiter (evening) 30 Moon between Pleiades, Hyades and Aldebaran (morning) 31 Aurigid meteor shower (unfavourable)

Moon:

Full Moon is on the 22 August and as usual there are several traditional names that you may see. It is sometimes described as the Sturgeon Moon after these large fish which were once very abundant in August.

Other names are the Corn Moon, the grain moon, and the red moon for the reddish hue it often takes on in the summer haze.

PLANETARY MOVEMENTS - THE ECLIPTIC

My monthly notes on talk about their movements, sometimes mentioning the Ecliptic. We all know the word but do we know what it really is? I thought that this month I would include a diagram to try to explain it simply.

The ancient Greeks referred to planets as “πλάνητες ἀστέρες” translated as 'planetes asteres' ('wandering stars') from which the word '' is derived, because they move across the celestial sphere relative to the .

Planets generally, but not exactly, follow the line of the ecliptic.

This “ecliptic” is the apparent path of the 's motion on the celestial sphere as seen from . It is tilted 23.5° with respect to the plane of the celestial since the Earth's spin axis is tilted at that angle with respect to its orbit around the sun. The ecliptic plane intersects the celestial equatorial plane along the line between the equinoxes. Have a good look at the diagram on the left.

A FEW NOTES ON OBSERVATIONS

Telescopic observers consider high altitude transits (when a celestial body crosses the observer's meridian, reaching its highest point in the sky) as more favourable than low altitude transits. At low altitudes the view of an object is through more atmosphere with the chance of greater distortions and turbulence as this diagram shows:

As a general rule, the best telescopic observation is done when a celestial body's altitude is greater than about 30°; hence observation in the couple of hours after rising or before setting is best avoided, unless there is no other alternative, which is very often the case.

Other factors of course can contribute to poor viewing, such as:  Poor atmospheric “seeing” (bad turbulence)  Observing over heat sources like rooftops and air conditioning vents  Observing from indoors through a window (can be done but don’t expect too much)  Not waiting for the telescope to acclimate to the surrounding air temperature  Looking at a planet without a lot of detail on it, such as Venus  Using inappropriate magnification (ie don’t use too much)  Poor collimation of the optics, or just poor optics  Inexperience

Planets this month:

So here is the usual run down of planetary movements for August.

Jupiter is in the South in Capricornus and is rapidly becoming the “star” of the night sky. With a small telescope or even binoculars you can spot Jupiter's biggest , whose positions change dramatically during the month. Fifth planet from the Sun, Jupiter, sometimes called the King of planets, reaches opposition on 19 August and reaches a peak altitude of 23.5° in true darkness, due south, at 01:22 BST. Of course Full Moon actually means that the Moon is at opposition, and it appears close in the SSW on 22 August. Jupiter will be shining at mag -2.9 and even through a modest sized telescope you should see some reasonable detail of the belts. Jupiter has been low as seen from the UK, as it tracked along the most southerly part of the ecliptic. This is now slowly changing, and the planet is gaining altitude with each passing year. At opposition it is in the Capricornus, but right on the eastern border with Aquarius.

Saturn is in the South in Capricornus with al altitude approaching 20°. On 2 August the planet is at opposition, in the opposite part of the sky to the Sun and visible all night given reasonable viewing conditions. Saturn’s rings should be nicely visible particularly at opposition.

Mars is in the West in Leo at an extremely low altitude. Observing really isn’t viable in August, as well as the low altitude the planet is dim at mag +1.8 and a tiny disk.

Venus is still low in the sky, in the West in Leo. Although shining at mag -4.0 it will be poorly positioned during August for observation. It is now an evening planet, setting an hour after the Sun.

Mercury is in the WNW in Leo at an extremely low altitude. observation is possible when it reaches superior conjunction on 1 August, after which it returns to the evening sky. The planet will be bright at mag -1.4 and if you are luck you may catch it for about half an hour after . Its altitude improves during the month but it will get fainter.

Uranus is just East of South in Aries and is a morning planet. Visibility is better in August at mag +5.7 and the planet also has a reasonable altitude improving from 20° to 49° at month end.

Neptune is in the South in Aquarius. It is still a morning planet but its position improves reaching 33° altitude at the middle of the month. At mag +7.8 you will need a small telescope to spot it, so why not set yourself a test if you haven’t ticked the planet off on your list yet.

International Space Station (ISS) forecast time for passes visible this month: Visit the Heavens Above website to check on forecast passes during August. [ source: https://www.heavens-above.com/ ]

A few visible passes this month, for early risers or insomniacs only I’m afraid:

Meteor Showers:

Perseid meteor shower

The annual Perseid meteor shower is usually the most reliable and spectacular of the meteor showers and this year conditions are very favourable with a new Moon on 8 August. The shower has high hourly rates, maybe 60 and hour, and bright meteors, caused by the Earth slamming into the debris left behind by 109P/Swift-Tuttle in July and August every year. They are called the Perseids because the meteors seem to originate from the constellation of Perseus, called the radiant.

The meteors can be seen at any time of night, but obviously the darker it is, and the clearer you have, the better your chances. At this time of year that probably means after midnight and preferably a night with the least , so around the new Moon on 8 August could be perfect. The peak is on the 12-13 August, but you can spot them anytime from around 16 July to 23 August so there is some flexibility to cover poor weather conditions.

The best way to see them? Well here are my top tips to maximise your enjoyment and success rate:

 Find a place where artificial lights do not spoil your viewing.  You won’t need any fancy equipment, you can just use your naked eyes, let them adjust to the dark.  A blanket or a comfortable chair - viewing meteors, just like any other kind of star gazing, is a waiting game, and you need to be comfortable. Take a flask of tea or coffee, or your favourite tipple, and relax.  Check the weather for your location and plan around this.  Some people mistakenly think that, since meteor showers have radiant points, you should look in the direction of the shower’s radiant point to see the most meteors. Not so! The meteors can appear in all parts of the sky.  Bring along a socially distanced friend or two to shout out “over there” - usually when you are looking in the opposite direction. Patience will be required.

As I said, theoretically the meteors originate in Perseus in the NNE, but it’s not important to specifically find that constellation – they can travel across the whole sky. So make sure you can see as much sky as possible, without obstruction from buildings or trees, to give yourself the best chance.

For photographs, the best set up is a DSLR on a tripod. Sorry, but smartphones won’t be cutting any mustard here. Use a wide angle lens and take a series of exposures of say 5 seconds, and keep on taking them. Believe me the instant you stop taking pictures is the time when a couple of insanely bright meteors will appear.

You will need to master full manual control of focus, ISO, aperture and shutter speed. To avoid star trails mount the camera on a tracking mount so that you can use longer exposures of, say, 30 seconds. An intervalometer is ideal because you can then just set the camera to take as many images you want as long as your batteries hold out.

DSLR on tracking mount WIRELESS INTERVALOMETER

Aurigid meteor shower

The Aurigid meteor shower will be active from 28 August to 5 September, producing its peak rate of meteors around 1 September, but is very much second best to the Perseids. The shower's radiant point is in the constellation Auriga, and at its peak, the shower is only expected to produce an hourly rate of around 5 meteors per hour (ZHR).

Good luck with your meteor watching. As always good luck and do let us know if you have any success.

Phenomena of the month of August (generated using Coelix Apex software):

PERTON LIBRARY GROUP (PLAG)

I have had queries from several people as to when PLAG is restarting.

Our group usually met on the third Thursday of every month but of course we have been unable to meet for well over a year. You will be aware that Perton Library is only just starting to reopen with limited access and facilities. Risk assessments are being prepared with a view to restarting meetings from 16 September.

The first PLAG meeting will be a talk night hosted by Doug Bickley and Steve Wootton, there’s lots to discuss and we will use the library projector to show some pictures. You will appreciate that it is unlikely that we will be able to let you handle any equipment. We will keep you informed and Scott Whitehouse will let us know how things stand then, but it may be for this meeting that we have to restrict numbers to ten. We hope to let you know the plan by the end of August and if necessary how to book.

WOLVERHAMPTON ASTRONOMICAL SOCIETY LECTURES

We are continuing with our programme of online lectures and will supplement these with “in person” meetings for astronomical events, so keep an eye on our social media for announcements. We also have regular Monday evening chat on Zoom throughout the year, the first 30 minutes for beginners to ask questions, in these sessions we give basic astronomy advice and swap tips, sometimes with a short talk.

Invitations to all talks are emailed to members. For the coming year Wolvas subscription will be only £10 per annum and you can sign up now our website www.wolvas.org.uk

Lectures online will only be available to paid-up members of Wolverhampton Astronomical Society. We continue to try and bring you some of the best speakers around and we have an exciting line up for the coming season. Our programme of speakers for next season 2021/22 has almost been filled.

The last lecture for the 2020/21 season:

09/08/21 Andy Briggs How to photograph a Black Hole: the Story of the Event Telescope

Lectures for the 2021/22 season:

13/09/21 Dr Steve Barrett The ABC of Galaxy Evolution 27/09/21 Steve Wootton The David Harris Lecture 11/10/21 AGM then short talk by member Adam Foster My Astronomy Journey 25/10/21 Prof Ian Morison Wonders of the Southern Sky 08/11/21 Martin Braddock Talk to be decided 22/11/21 Alex Binks Young Stars in our Backyard 06/12/21 Georgia Pulford A Brief Geological History of Time 10/01/22 Prof Rene Breton Talk to be decided 24/01/22 Dr Julian Onions Crazy Interstellar Rockets 07/02/22 Steve Clifton Then and Now 21/02/22 Mike Frost Talk to be decided 07/03/22 # not booked yet # Annual free public Paul Pope Lecture 21/03/22 Pete Williamson The Moons of our Solar System 11/04/22 Paul Fellows Talk to be decided 16/05/22 Damian Hardwick The Life of Albert Einstein 13/06/22 # not yet booked yet #

Watch out for updates As well as our webpage www.wolvas.org.uk we will be posting details of events on social media, so keep an eye on our Facebook (https://www.facebook.com/wolvasuk) and Twitter (https://twitter.com/wolvasuk) accounts for the latest updates and news.